BinderHub frontend package

[jtpio]

A few parts from the default BinderHub frontend could be reused for the gallery:

• the BinderImage abstraction, that would hide implementation details such as the use of an EventSource
• handling of the different providers

There is an issue on the binderhub repo about the long term planning for the frontend: jupyterhub/binderhub#774

One way forward could be to have a common client package that would provide a basic set of functionalities to interact with a BinderHub deployment.

[yuvipanda]

There is now https://github.com/jupyterhub/binderhub/tree/main/js/packages/binderhub-client, published as @jupyterhub/binderhub-client on NPM. I've been cleaning it up a lot more in the last week or so, and the next version out should be pretty usable

[jtpio]

Nice thanks @yuvipanda for the heads-up!

[jtpio]

Marking as "help wanted" in case someone would like to take a closer look at how this package could be used in this repo.